"A lot of the insanity that happened in the Halloween episode, it gets touched on throughout the season," said Allen, whose character, Toby Cavanaugh, was recently revealed to be part of the villainous A team. "There's a lot of secrets that happen on the train and we find out a lot more of what's tormenting the girls and pushing the girls toward their breaking point."

Blackburn -- who plays Hanna Marin's boyfriend, Caleb Rivers -- added, "Everybody has their own secrets on the show. I think it's sort of a reflection of life. As life goes on, everybody's dirty secrets are revealed."

Keegan Allen and Tyler Blackburn

The long-haired actor hinted there may be more in store for Caleb this season. "For my character, his [secrets] have been pretty tame, and I think they'll continue to be mostly stuff about his past and his family. I think there's always room for more."

Viewers aren't the only ones who can't get enough of the show's numerous twists and turns, according to Allen. "You read every script and you're like, 'Oh, my gosh! How are they going to make this work?'"